This invention relates to orthotics and specifically to orthotics that fit a foot and a shoe. The invention particularly relates to orthotics formed in a casting shell that conforms to the contours of the last of the patient's shoe.
Orthotics are known in the prior art. See for example, Meyer, U.S. Pat. No. 4,669,142; Sloane, U.S. Pat. No. 2,742,657; Daley, U.S. Pat. No. 4,979,252; and Cumberland, U.S. Pat. No. 4,888,841.
Although ready-made and custom-made orthotics have been known in the prior art there are two outstanding obstacles that interfere with the success of these products. First, there is the problem in matching the orthosis to the contour of the insole of the shoe it is to be worn in, as well as the foot's plantar surface. This is particularly the case when an orthotic technician is making soft or flexible orthotics. This takes considerable skill and some art work. If these two surfaces fail to mate perfectly the orthosis will distort under body weight and take the shape of the shoe, thus losing accommodation.
Another major problem is the fact that the foot does not always fall into the range of standard shoe sizes, widths, and last shapes, and even with a custom-made orthosis to fit a foot, the orthosis may not fit the shoe. This will mean that the orthosis may help with symptoms but may not address the cause of the problem.
The present invention makes it possible to accommodate many people in ready-made shoes who now must have their shoes custom-made. This will greatly increase their shoe style selection and reduce their costs. Additionally, there are thousands of people who badly need custom-made shoes but cannot afford them and have suffered greatly as a result. With this invention, many of them will be able to be fitted comfortably in ready-made shoes.
According to the present invention a casting shell for making an orthosis to conformingly fit a shoe and a patient's foot within the shoe comprises a shell piece which conforms to a portion of a last of the shoe, the shell piece having an opening to allow removal from the patient's foot, a mating shell piece which conforms to the rest of the last of the shoe, means for injecting an insole forming material into said shell, and means for fastening the shell pieces together about a foot.
In a preferred embodiment of the present invention a casting shell is provided for making an insole to conformingly fit a shoe and a patient's foot within the shoe. The casting shell comprises an upper shell half which conforms to a last of the shoe, the upper shell half having an opening flange to allow removal from the patient's foot, a lower shell half which conforms to the last of the shoe and has an aperture in the medial arch area, an injector tube coupled to the aperture in the lower shell half for injecting insole forming material, fasteners for fastening the upper and lower shell halves together, and a clamp for maintaining the opening flange in the closed position while injecting insole forming material.
The present invention also comprises a method for making an insole to conformingly fit a shoe and a patient's foot within the shoe. The method comprises the steps of obtaining an appropriate sized shoe having a deep last to provide room to accommodate the insole and the foot, obtaining a shell made from the last from which the shoe is made, placing the patient's foot in the shell, injecting a curable insole forming material under and about the patient's foot to fit the contour of the foot and the interior of the shell, curing the insole forming material, and removing the insole and placing it in the shoe.
In a preferred embodiment of the invention, the shell has an upper shell half and a lower shell half joined together at a parting line about generally the largest perimeter of the shell and means for fastening the upper and lower shell halves together. Insole forming material is then injected into the lower shell half under and about the patient's foot to form a shape that fits the patient's foot and the shell.
To practice the invention, spacing tape may be affixed to the bottom sides of the last from which the patient's shoe is made. The spacing tape should have a thickness that is substantially equal to that of the lower shell half material. The last is then inverted in a sand casting box and a suitable casting material such as Liquid Last, a product of Riecken's Orthotic Laboratory, which material is made from talc, polyester resin, and microcellular glass beads or plaster, is poured over the last to form a mold. The mold should have the proper heel height for the last cast into it. The edges of the mold should turn up around the sides of the last to the last's widest perimeter leaving a ledge along the edge of the last for the upper half of the casting shell to mate with.
This mold of Liquid Last can be used as the lower shell half, however it is an opaque, heavy, and solid block of expensive material. Thus, for production purposes it may be modified slightly and used as a master mold for forming the production casting shells on a vacuum forming machine. The mold is removed, trimmed as appropriate, and holes are drilled through the mold to communicate a vacuum from the vacuum forming machine to the material to be vacuum formed. A heated blank of lower shell half material is placed over the mold on the vacuum forming machine and drawn down by the vacuum forming machine. That lower shell half is then removed from the mold and a second blank of lower shell half material is drawn down to form a second lower shell half. One of those lower shell halves is put aside for use as the lower portion of a casting shell, and the other lower shell half has holes drilled through it to coincide and align with the holes previously drilled in the mold. These holes are drilled to allow the vacuum to communicate between the vacuum forming machine and the upper shell half material to be formed by the vacuum forming machine. The second lower shell half is then reinserted in the mold and the last is placed therein. A notch is cut through the lower shell half and into the mold at a position adjacent to the heel curve of the last. A flange forming piece is then mounted on the last and the last is inserted into the foot receiving cavity of the lower shell half ensuring that the flange forming piece engages the notch in the lower shell half and the mold. A blank of upper shell half material is then drawn down over the last and the lower shell half. The upper shell half is removed and trimmed to provide a hole for the ankle and to allow the upper shell half opening flange to open and close. The upper shell half is laid on and aligned with the lower shell half and fastener receiving holes are drilled through mating flanges formed in the shell halves. Injector tube holes are drilled in the medial arch area to accommodate a filler tube for injecting the insole forming materials.
In one preferred embodiment of the invention, an insole cover is placed in the foot receiving cavity of the lower shell half, the patient's foot is placed on the insole cover, and the position of the fastener receiving holes are marked on the insole cover. The insole cover is removed, the holes are punched through, and the insole cover is replaced in the foot receiving cavity. The patient's foot is lightly placed on top of the insole cover and the insole cover is then adjusted to align the holes punched therein to align with the fastener receiving holes. The upper shell half is then placed over the patient's foot and fasteners are inserted through the fastener receiving holes, thereby joining the upper shell half, the lower shell half, and holding the insole cover therebetween. Insole forming material is then injected through the injection tube into the lower shell half under and about the patient's foot.
The present invention can be practiced for various purposes. One such use is as a sizing device. The clear plastic casting shell base alone lets you see at a glance, once a foot is placed in it, if the size is proper. These bases would be of great assistance as fitting devices in all shoe stores, even self-service stores. A second use would be to improve fit and comfort of ready-made footwear to the extent that in many cases ready-made footwear can be made as comfortable as custom-made footwear. By sizing patients in casting shells, in accordance with the invention, a technician can determine the true insole size needed for comfort and proper function and can form insoles that will be the exact shape of feet and thick enough to take up any excess room in ready-made shoes.
A third use of the casting shells would be to serve as a mold to cast, fabricate, or heat form custom orthosis for the foot's plantar surface area. After the proper size shell has been selected, it is used as a form in which to assemble needed modalities on a full or partial insole to make a custom orthotic.
Another and important use of the casting shell is to accommodate partial amputations and/or mis-mated foot conditions. When dealing with major amputations, the bottom of the orthosis can be made up in the casting shell out of fiberglass. This gives the rigidity needed to prevent the shoe from folding back and it also becomes a spring that stores energy from the gait cycle to aid in toe off situations. If the amputation has been rather extensive, such as a chopart, lisfranc, or transmetatarsal, a filler block of flexible foam may be formed. It can be made of urethane or silicone foam and can be formed in the casting shell so as to become part of the orthotic. It preferably should not extend closer than one-half inch to the anterior end of the foot, this remaining space being filled with accommodative visco elastic polymer. This saves considerable weight, eliminates the need for a high, rigid rocker and improves function.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.